SU939597A1 - Method for electrically depositing cadmium - Google Patents

Description

(54) METHOD OF ELECTRIC SUPPLY OF CADMIUM

The invention relates to non-ferrous metallurgy (hydroelectric metallogy of metal metals) and can be used for the electrolytic production of cadmium from sulphate electrolytes.

A known method for producing cadmium under stationary conditions or using rotating cathodes. The washed cathode sediment is washed in water and briquetted with further remelting and refining l.

However, cathode cadmium is obtained in a non-compact form, which complicates its further processing.

The closest to the present invention is the well-known method of electrodeposition of cadmium from sulphate electrolytes with the addition of stollen bone glue as a surface active additive 2.

However, table glue reduces the metal yield by 2-4%, accumulates in the electrolyte, contaminates it and degrades the quality of cathodic cadmium, besides, glue is a scarce and expensive product.

The purpose of the invention is to increase the current output of cadmium and increase the purity of the metal.

This goal is achieved by the fact that the electroplating of cadmium from sulphate electrolytes is carried out with the continuous introduction of sodium, as a surface active substance, in an amount of 1-3 kg / ton to the electrolyte silicate.

The method is carried out as follows.

ten

The liquid glass solution, which is obtained by boiling in water, a spiked steam of a separate lump of sodium silicate, is supplied continuously as a surfactant together with a feed electrolyte to cadmium electrolysis baths.

Example. The industrial test conditions are as follows. Cathode current density 52 A / m, cadmium content

20 in the working electrolyte 50-55 g / l, the content of sulfuric acid in the electrolyte is 110-120 g / l, the circulation ratio is 6-7, the electrolyte temperature is 29-30 s, the duration of cathode buildup

25 sediment 24 hours, the total test duration is 7 days. At the time of testing, the content of lead impurities in the cathode cadmium and electrolyte is controlled, the appearance of the cathode

0 cadmium precipitate, cadmium current output.

Surfactant (liquid glass) set in electr. lit in the form of a 25% aqueous solution (unit weight 1.16-1.20 g / cm).

The test results are presented in the table in comparison with the data obtained using table glue (1.5 kg / ton) as a surfactant and without the addition of a surfactant.

From the data in the table it follows that replacing stoller glue with liquid glass leads to a positive result both in cadmium yield in current and in reducing the main limiting impurity of lead. stable lower lead concentration in cadmium from 0.0065 to 0.005% or less, as well as in cadmium electrolyte. The increase in surfactant consumption is 3.0 kg / ton, although it does not have a significant effect. It is undesirable to reduce lead impurities in cadmium and electrolyte, since the spent cadmium electrolyte is wrapped in the leaching of Cu-Cd cake. With an excess of silicic acid; 1% in solutions the sludge deteriorates, and the filtration process is slowed down.

The introduction of liquid glass in the electrolysis process is advisable in the form of a 25% aqueous solution. A lower concentration of surfactant introduces an excess amount of water and lowers the concentration of cadmium in the electrolyte. High concentration of liquid glass (more than 35%) is poorly soluble in the acidic electrolyte, local areas of gel aggregation are formed.

The positive effect of liquid glass on the increase in cadmium purity in terms of the lead impurity content in the cathode metal is due to the fact that the silicic acid binds the lead ions present in the electrolyte to a non-soluble precipitate.

The economic effect from the use of sodium silicate as a surfactant will be 8.25 rubles / ton of cadmium.

7939597

Claims (2)

Claims in sodium silicate electrolyte in The way of cadmium electroosheni in the amount of 1-3 kg / t, sulphate electrolytes, containing information sources, surfactants taken into account in the examination characterized in that, 5 1. USSR copyright certificate in order to increase the yield of 1 cadmium in accordance with No. 156521, cl. C 25 C 1/16 1961. current and increase the purity of the mark, 2. Chizhikov. Cadmium, M., the process is carried out with continuous input-Science, 1967, p. 152-156. as surface active ve